I will self transfer Madrid > Stansted > Stockholm. Being European, what do I ne...

I am a Spaniard (European citizen).

I have a flight with Ryanair, which would go Madrid-Stansted, arriving at 11:35pm, and a later flght Stansted-Stockholm, leaving the next morning.

With the whole Brexit ordeal, I am left clueless about... well, everything:

• Do I need to do passport control? Do I need a visa? Am I allowed to leave the airport? Would I need a visa for that specifically?
• Further, from what I've read the terminal is closed from 00:00 to 02:00.
• What does this mean? Would I be forced to leave the airport for that time?

Do I need to do passport control?

AIUI the only airports in the UK with "airside transit" are Heathrow, Gatwick and Manchester. At all others you will have to pass through passport control.

Do I need a visa?

A the time the question was asked, you did not need a Visa or other advance authorization to transit through the UK or to visit the UK for tourism or business.

However, since the 2nd April 2025, EU citizens will require a ETA to travel to and enter the UK. "airside transits" are currently exempted from this scheme but "landside transits" are not.

https://www.gov.uk/guidance/apply-for-an-electronic-travel-authorisation-eta

Am I allowed to leave the airport?

At an airport without "airside transit" facilities you will have to go through the regular arrivals flow, which (assuming you are admitted to the country) will leave you in the "public" part of the airport. Whether you chose to leave the airport at that point, or start the departure process for your next flight immediately is generally up to you.

But you have the additional wrinkle that your self-connection is "overnight".

What does this mean? Would I be forced to leave the airport for that time?

It's quite likely that you could be forced to leave the airport terminal when it closes at night until it reopens in the morning.